Mask Defoggers Explained

Regardless of the brand or type of defog there are basically only two
ways to defog your mask, either coat the lens with an inhibitor (gels
like SeaGold, Nitrocellulose, and of course 'spit') or make the lens very clean
so fog doesn't form (surfactants like SeaQuick, SeaDrops, and baby shampoo). Both
approaches work equally well but require different application methods
so it's mostly a matter of personal preference.

A cleaning spray is the most popular approach because it's
quick and easy. Generously spray the inside of the mask lens, rub and
rinse completely to remove. If the lens is not 'squeeky clean' then
repeat and perhaps rub a bit harder.

The liquid drops are a concentrated version of the spray type
cleaners and thus a better value. Wet the lens first, add a drop in
each lens, rub and rinse completely to remove. Some people who like
concentrated cleaners prefer to use Johnsons 'No More Tears' Baby
Shampoo®, it's effective even if a bit harsh.

With the gel, apply a thin even coating to the inside of the
mask lens (more is not better) and lightly rinse to smooth out the
coating. Do NOT completely rinse or rub away the gel, remember you want a light coating of the gel on the lens.

With the nitrocellulose solution, apply a thin even coating to the inside of the mask lens, but DO NOT rinse, then allow to dry before use.

Every once in a while it doesn't hurt to also clean the outside
of the mask lens. It won't help to prevent fogging but you'll see
better if the lens is clean on both sides! By the way, we are not big
fans of the 'mask bucket' found on many dive boats. When everyone is
rinsing their masks in the same bucket, they are sharing their bacteria
and viruses with everyone else. We avoid that by rinsing our masks in
seawater (works fine), fresh water from the shower hose if there is one,
or even bottled water as a last resort.